U.S. patent application number 15/786144 was filed with the patent office on 2018-02-08 for channel information feedback method and device.
The applicant listed for this patent is China Mobile Communications Corporation. Invention is credited to Hui Tong.
Application Number | 20180041258 15/786144 |
Document ID | / |
Family ID | 57125637 |
Filed Date | 2018-02-08 |
United States Patent
Application |
20180041258 |
Kind Code |
A1 |
Tong; Hui |
February 8, 2018 |
CHANNEL INFORMATION FEEDBACK METHOD AND DEVICE
Abstract
In an embodiment, a Node B configures a first Channel State
Information-Reference Signal (CSI-RS) and ports configured to send
the first CSI-RS; and the Node B sends the first CSI-RS to User
Equipment (UE) at the configured ports. Therefore, downlink channel
information feedback in Three-Dimensional Multiple-Input
Multiple-Output (3D-MIMO) may be supported.
Inventors: |
Tong; Hui; (Beijing,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
China Mobile Communications Corporation |
Beijing |
|
CN |
|
|
Family ID: |
57125637 |
Appl. No.: |
15/786144 |
Filed: |
October 17, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/CN2016/079454 |
Apr 15, 2016 |
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15786144 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 1/06 20130101; H04W
72/0413 20130101; H04B 7/0639 20130101; H04L 5/0023 20130101; H04B
7/0456 20130101; H04B 7/0417 20130101; H04W 72/042 20130101; H04B
7/0626 20130101; H04B 7/0632 20130101 |
International
Class: |
H04B 7/0417 20060101
H04B007/0417; H04B 7/06 20060101 H04B007/06; H04W 72/04 20060101
H04W072/04; H04B 7/0456 20060101 H04B007/0456 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 17, 2015 |
CN |
201510184679.9 |
Claims
1. A channel information feedback method, comprising: configuring,
by a Node B, a first Channel State Information-Reference Signal
(CSI-RS) and ports configured to send the first CSI-RS; and
sending, by the Node B, the first CSI-RS to User Equipment (UE) at
the configured ports, the first CSI-RS being configured for the UE
to perform downlink channel measurement and feed back first
downlink channel information; wherein the method further comprises:
configuring, by the Node B, a second CSI-RS and ports configured to
send the second CSI-RS; and sending, by the Node B, the second
CSI-RS to the UE at the ports configured to send the second CSI-RS,
the second CSI-RS being configured for the UE to feed back a
channel Rank Indication (RI); wherein the second CSI-RS is an
un-precoded CSI-RS.
2. The method according to claim 1, wherein the first CSI-RS is a
precoded CSI-RS.
3. The method according to claim 1, wherein a number of the ports
configured to send the first CSI-RS is smaller than or equal to a
number of receiving antennae of the UE.
4. The method according to claim 3, wherein the number of the ports
configured to send the first CSI-RS is two, and the two ports
correspond to different polarization directions of antennae of the
Node B.
5. The method according to claim 1, wherein the first downlink
channel information comprises a Channel Quality Indicator (CQI)
and/or a Precoding Matrix Indicator (PMI).
6. The method according to claim 5, wherein if the first CSI-RS is
a CSI-RS of two ports, the first downlink channel information
comprises the CQI and the PMI; and if the first CSI-RS is a CSI-RS
of a single port, the first downlink channel information comprises
the CQI.
7. The method according to claim 1, wherein sending, by the Node B,
the second CSI-RS to the UE comprises: sending, by the Node B, the
second CSI-RS to the UE on part of occupied antennae.
8. The method according to claim 1, wherein the number of the ports
configured to send the first CSI-RS is smaller than or equal to a
number of the ports configured to send the second CSI-RS.
9. The method according to claim 2, wherein configuring, by the
Node B, the first CSI-RS comprises: determining, by the Node B,
uplink channel information according to an uplink Sounding
Reference Signal (SRS) sent by the UE; estimating, by the Node B,
second downlink channel information on the basis of the determined
uplink channel information, and determining precoding matrix
information when downlink data is sent to the UE on the basis of
the estimated second downlink channel information; and configuring,
by the Node B, the first CSI-RS on the basis of the determined
precoding matrix information.
10. The method according to claim 2, wherein configuring, by the
Node B, the first CSI-RS comprises: configuring, by the Node B, a
second CSI-RS and ports configured to send the second CSI-RS;
sending, by the Node B, the second CSI-RS to the UE at the ports
configured to send the second CSI-RS to enable the UE to feed back
third downlink channel information; and configuring, by the Node B,
the first CSI-RS on the basis of precoding matrix information when
the first CSI-RS is sent to the UE.
11. The method according to claim 10, wherein configuring, by the
Node B, the first CSI-RS further comprises: determining, by the
Node B, the precoding matrix information when the first CSI-RS is
sent to the UE on the basis of the third downlink channel
information fed back by the UE.
12. A channel information feedback method, comprising: receiving,
by User Equipment (UE), a first Channel State Information-Reference
Signal (CSI-RS) sent by a Node B; performing, by the UE, downlink
channel measurement to determine first downlink channel information
on the basis of the first CSI-RS; and feeding back, by the UE, the
first downlink channel information to the Node B; wherein the
method further comprises: receiving, by the UE, a second CSI-RS
sent by the Node B; and performing, by the UE, downlink channel
measurement on the basis of the second CSI-RS, and feeding back a
channel Rank Indication (RI) on the basis of a channel measurement
result; wherein the second CSI-RS is an un-precoded CSI-RS.
13. The method according to claim 12, wherein the first CSI-RS is a
precoded CSI-RS.
14. The method according to claim 12, wherein the first downlink
channel information comprises a Channel Quality Indicator (CQI)
and/or a Precoding Matrix Indicator (PMI).
15. The method according to claim 12, wherein if the first CSI-RS
is a CSI-RS of two ports, the first downlink channel information
comprises the CQI and the PMI; and if the first CSI-RS is a CSI-RS
of a single port, the first downlink channel information comprises
the CQI.
16. The method according to claim 12, wherein, before the UE
receives the first CSI-RS sent by the Node B, the UE receives the
second CSI-RS sent by the Node B.
17. The method according to claim 12, further comprising:
receiving, by the UE, a second CSI-RS sent by the Node B; and
performing, by the UE, downlink channel measurement on the basis of
the second CSI-RS, and feeding back third downlink channel
information, the third downlink channel information being
configured for the Node B to determine precoding matrix information
for configuring the first CSI-RS.
18. A channel information feedback device, comprising one or more
processors and a storage medium storing computer-readable operation
instructions, wherein when the computer-readable operation
instructions in the storage medium are run, the processor is
configured to: configure a first Channel State
Information-Reference Signal (CSI-RS) and ports configured to send
the first CSI-RS; send the first CSI-RS to User Equipment (UE) at
the configured ports, the first CSI-RS being configured for the UE
to perform downlink channel measurement and feed back first
downlink channel information; configure a second CSI-RS and ports
configured to send the second CSI-RS; and send the second CSI-RS to
the UE at the ports configured to send the second CSI-RS, the
second CSI-RS being configured for the UE to feed back a channel
Rank Indication (RI); or when the computer-readable operation
instructions in the storage medium are run, the processor is
configured to: receive a first CSI-RS sent by a Node B; perform
downlink channel measurement to determine first downlink channel
information on the basis of the first CSI-RS; feed back the first
downlink channel information to the Node B; receive a second CSI-RS
sent by the Node B; and perform downlink channel measurement on the
basis of the second CSI-RS, and feeding back a channel RI on the
basis of a channel measurement result; wherein the second CSI-RS is
an un-precoded CSI-RS.
19. The device according to claim 18, wherein the first CSI-RS is a
precoded CSI-RS.
20. The device according to claim 18, wherein the first downlink
channel information comprises a Channel Quality Indicator (CQI)
and/or a Precoding Matrix Indicator (PMI).
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The application is a continuation application of
International Application No. PCT/CN/2016/079454 filed on Apr. 15,
2016, which claims priority to Chinese Patent Application No.
201510184679.9 filed on Apr. 17, 2015. The applications are
incorporated herein by reference in its entirety.
TECHNICAL FIELD
[0002] The disclosure relates to the field of communication
technology, and particularly to a channel information feedback
method and device.
BACKGROUND
[0003] In a Multiple-Input Multiple-Output (MIMO) transmission
manner, a Node B may perform data transmission with User Equipment
(UE) by using multiple antenna ports. In a communication system in
a related technology, antennae of a Node B are usually deployed in
a horizontal arrangement with a smaller number. For example, in a
Long Term Evolution (LTE) system, a number of antenna ports of an
evolved Node B is 1, 2, 4 or 8 at present.
[0004] A Node B is required to perform downlink data scheduling on
the basis of downlink channel information fed back by UE. For this,
the UE is required to perform a channel measurement. Along with the
development of an antenna technology, an antenna array may be
enhanced from a current horizontal arrangement into a
Three-Dimensional (3D) and vertical arrangement, and a number of
antennae of a Node B may thus also be sharply increased, for
example, increased to 16, 32, 64, 128 and even more. Therefore,
3D-MIMO transmission is formed.
[0005] There is yet no related solution capable of supporting
downlink channel information feedback in 3D-MIMO in the related
technology.
SUMMARY
[0006] Embodiments of the disclosure provide a channel information
feedback method and device, which are used for supporting downlink
channel information feedback in 3D-MIMO.
[0007] An embodiment of the disclosure provides a channel
information feedback method, which may include that:
[0008] a Node B configures a first Channel State
Information-Reference Signal (CSI-RS) and ports configured to send
the first CSI-RS; and
[0009] the Node B sends the first CSI-RS to UE at the configured
ports, the first CSI-RS being configured for the UE to perform
downlink channel measurement and feed back first downlink channel
information.
[0010] Optionally, the first CSI-RS may be a precoded CSI-RS.
[0011] Optionally, a number of the ports configured to send the
first CSI-RS may be smaller than or equal to a number of receiving
antennae of the UE.
[0012] Optionally, the number of the ports configured to send the
first CSI-RS may be two, and the two ports may correspond to
different polarization directions of antennae of the Node B.
[0013] Optionally, the first downlink channel information may
include a Channel Quality Indicator (CQI) and/or a Precoding Matrix
Indicator (PMI).
[0014] Optionally, if the first CSI-RS is a CSI-RS of two ports,
the first downlink channel information may include the CQI and the
PMI; and
[0015] if the first CSI-RS is a CSI-RS of a single port, the first
downlink channel information may include the CQI.
[0016] Optionally, the operation that the Node B configures the
first CSI-RS may include that:
[0017] when the UE is required to perform single-stream
transmission, the Node B configures a first CSI-RS of a single
port; and
[0018] when the UE is required to perform double-stream
transmission, the Node B configures a first CSI-RS of two ports,
the two ports corresponding to different polarization directions of
the antennae of the Node B.
[0019] Optionally, before the operation that the Node B configures
the first CSI-RS and the ports configured to send the first CSI-RS,
the method may further include that:
[0020] the Node B configures a second CSI-RS and ports configured
to send the second CSI-RS; and
[0021] the Node B sends the second CSI-RS to the UE at the
configured ports configured to send the second CSI-RS, the second
CSI-RS being configured for the UE to feed back a channel Rank
Indication (RI).
[0022] Optionally, the second CSI-RS may be a CSI-RS which is not
precoded.
[0023] Optionally, the operation that the Node B sends the second
CSI-RS to the UE may include that:
[0024] the Node B sends the second CSI-RS to the UE on part of
occupied antennae.
[0025] Optionally, the number of the ports configured to send the
first CSI-RS may be smaller than or equal to a number of the ports
configured to send the second CSI-RS.
[0026] Optionally, the operation that the Node B configures the
first CSI-RS may include that:
[0027] the Node B determines uplink channel information according
to an uplink Sounding Reference Signal (SRS) sent by the UE;
[0028] the Node B estimates second downlink channel information on
the basis of the determined uplink channel information, and
determines precoding matrix information when downlink data is sent
to the UE on the basis of the estimated second downlink channel
information; and
[0029] the Node B configures the first CSI-RS on the basis of the
determined precoding matrix information.
[0030] Optionally, the operation that the Node B configures the
first CSI-RS may include that:
[0031] the Node B configures the second CSI-RS and the ports
configured to send the second CSI-RS;
[0032] the Node B sends the second CSI-RS to the UE at the
configured ports configured to send the second CSI-RS to enable the
UE to feed back third downlink channel information;
[0033] the Node B determines the precoding matrix information when
the downlink data is sent to the UE on the basis of the third
downlink channel information fed back by the UE; and
[0034] the Node B configures the first CSI-RS on the basis of the
determined precoding matrix information.
[0035] Another embodiment of the disclosure provides a channel
information feedback method, which may include that:
[0036] UE receives a first CSI-RS sent by a Node B;
[0037] the UE performs downlink channel measurement to determine
first downlink channel information on the basis of the first
CSI-RS; and
[0038] the UE feeds back the first downlink channel information to
the Node B.
[0039] Optionally, the first CSI-RS may be a precoded CSI-RS.
[0040] Optionally, the first downlink channel information may
include a CQI and/or a PMI.
[0041] Optionally, if the first CSI-RS is a CSI-RS of two ports,
the first downlink channel information may include the CQI and the
PMI; and
[0042] if the first CSI-RS is a CSI-RS of a single port, the first
downlink channel information may include the CQI.
[0043] Optionally, before the operation that the UE receives the
first CSI-RS sent by the Node B, the method may further include
that:
[0044] the UE receives a second CSI-RS sent by the Node B; and
[0045] the UE performs downlink channel measurement on the basis of
the second CSI-RS, and feeds back a channel RI on the basis of a
channel measurement result.
[0046] Optionally, before the operation that the UE receives the
first CSI-RS sent by the Node B, the method may further include
that:
[0047] the UE receives the second CSI-RS sent by the Node B;
and
[0048] the UE performs downlink channel measurement on the basis of
the second CSI-RS, and feeds back third downlink channel
information, the third downlink channel information being
configured for the Node B to determine precoding matrix information
for configuration of the first CSI-RS.
[0049] Optionally, the second CSI-RS may be a CSI-RS which is not
precoded.
[0050] An embodiment of the disclosure provides a channel
information feedback device, which may include:
[0051] a configuration module, configured to configure a first
CSI-RS and ports configured to send the first CSI-RS; and
[0052] a sending module, configured to send the first CSI-RS to UE
at the configured ports, the first CSI-RS being configured for the
UE to perform downlink channel measurement and feed back first
downlink channel information.
[0053] Another embodiment of the disclosure provides a channel
information feedback device, which may include:
[0054] a receiving module, configured to receive a first CSI-RS
sent by a Node B;
[0055] a determination module, configured to perform downlink
channel measurement to determine first downlink channel information
on the basis of the first CSI-RS; and
[0056] a sending module, configured to feed back the first downlink
channel information to the Node B.
[0057] In the embodiments of the disclosure, the Node B configures
the first CSI-RS and the ports configured to send the first CSI-RS;
and the Node B sends the first CSI-RS to the UE at the configured
ports. Therefore, downlink channel information feedback in 3D-MIMO
may be supported.
BRIEF DESCRIPTION OF DRAWINGS
[0058] In order to describe the technical solutions in the
embodiments of the disclosure or in the related technology more
clearly, drawings required to be used for descriptions about the
embodiments or the related technology will be simply introduced
below. Obviously, the drawings in the following descriptions are
only some embodiments recorded in the disclosure. Those skilled in
the art may further obtain other drawings according to these
drawings without creative work. The following drawings are not
intentionally drawn in an equal scaling manner according to
practical sizes, and focus on presenting the theme of the
disclosure.
[0059] FIG. 1 is a flowchart of a channel information feedback
method according to some embodiments of the disclosure.
[0060] FIG. 2 is a schematic diagram of feeding back a phase
difference and a CQI by UE.
[0061] FIG. 3 is a schematic diagram of sending a Rank
Indication-Reference Signal (RI-RS) and a short-term CSI-RS.
[0062] FIG. 4 is a schematic diagram of feeding back an RI by
sending a CSI-RS through part of ports.
[0063] FIG. 5 is a flowchart of a channel information feedback
method according to some other embodiments of the disclosure.
[0064] FIG. 6 is a flowchart of a channel information feedback
method according to some other embodiments of the disclosure.
[0065] FIG. 7 is a structure diagram of a channel information
feedback device according to some other embodiments of the
disclosure.
[0066] FIG. 8 is a structure diagram of a channel information
feedback device according to some other embodiments of the
disclosure.
DETAILED DESCRIPTION
[0067] In order to make the purposes, technical solutions and
advantages of the embodiments of the disclosure clearer, the
technical solutions of the embodiments of the disclosure will be
described clearly and completely below in combination with the
drawings of the embodiments of the disclosure. Obviously, the
described embodiments are not all embodiments but only part of
embodiments of the disclosure. All other embodiments obtained by
those skilled in the art on the basis of the described embodiments
of the disclosure fall within the scope of protection of the
disclosure.
[0068] At first, related technical thoughts involved in the
embodiments of the disclosure will be introduced.
[0069] First, thought of determining downlink channel information
on the basis of channel reciprocity
[0070] A Node B may measure an uplink SRS sent by a terminal and
estimate downlink channel information on the basis of a measurement
result and channel reciprocity. Compared with a codebook-based
feedback manner, such a manner may better support a downlink
multi-antenna transmission manner.
[0071] In a 3D-MIMO system, a Node B introduces an antenna array in
both horizontal and vertical dimensions, which greatly increases a
number of antennae compared with a previous antenna array only in
the horizontal dimension. If a conventional codebook-based feedback
manner is still used, along with increase of the number of the
antennae of the Node B, reference signal overhead for downlink
channel measurement will be linearly increased. In addition, the
two-dimensional antenna array is diversified in form, and
difficulties in codebook design will also be greatly increased, so
that it is difficult to achieve a sufficient performance gain under
a certain codebook size limit. Channel-reciprocity-based downlink
channel estimation will not increase uplink SRS overhead as the
number of the antennae increases, and is also not required to
design a new codebook, so that a better performance gain may be
achieved.
[0072] Therefore, the channel reciprocity may effectively obtain
downlink channel information and better support the downlink
multi-antenna transmission manner. Particularly in the 3D-MIMO
system, due to the fact that the number of the antennae is greatly
increased, determination of the downlink channel information on the
basis of the channel reciprocity has more advantages compared with
the conventional codebook-based manner. The channel reciprocity is
mainly applied to a Time Division Duplexing (TDD) system, and may
also be applied to a Frequency Division Duplexing (FDD) system.
[0073] Second, coding information required by data sending of the
Node B includes a precoding matrix and a Modulation and Coding
Scheme (MCS)
[0074] The Node B may determine the precoding matrix required by
sending data on the basis of the downlink channel information
obtained according to the channel reciprocity. Besides the
precoding matrix, the Node B is also required to determine the MCS
for downlink data transmission. The MCS is determined on the basis
of a signal to interference and noise ratio of a received signal of
UE, wherein a signal intensity is determined by an uplink SRS, but
an interference intensity (mainly including neighboring cell
interference) cannot be determined by the uplink SRS.
[0075] For feeding back the interference intensity, the UE may feed
back a downlink reference signal-based CQI to the Node B. The
interference intensity may be estimated by comparing the CQI fed
back by the UE with an intensity of the uplink SRS. For example,
when the CQI fed back by the UE is much lower than the intensity of
the uplink SRS, it may be determined that the interference
intensity is higher. The Node B may determine the MCS by combining
the estimated interference intensity and the intensity of the
uplink SRS.
[0076] Third, problems for CQI feedback and channel reciprocity
[0077] At first, the CQI fed back by the UE is mismatched with a
transmission mode for downlink data transmission of the Node B.
Although the Node B may determine the MCS required by downlink data
transmission according to the CQI fed back by the UE and the uplink
SRS, the CQI fed back by the UE corresponds to a
sending-diversity-based transmission mode used by the Node B and is
mismatched with the transmission mode practically used by the Node
B for downlink data transmission. Therefore, the Node B cannot
directly use the CQI fed back by the UE, but is required to
compensate the CQI, which increases processing difficulties.
Moreover, the CQI fed back by the UE is quantized, and cannot be
inaccurately compensated, so that downlink transmission performance
is reduced. The problems are more serious in the 3D-MIMO system:
along with great increase of the number of the antennae, a
beamforming gain achieved when downlink data is practically sent is
more obvious, while the two-antenna sending diversity-based CQI fed
back by the UE is unrelated to a number of antennae of the Node B
for downlink data transmission, so that the CQI fed back by the UE
is more mismatched with a CQI practically used for downlink data
transmission.
[0078] Second, uplink and downlink channels only have partial
channel reciprocity. In a practical application, a sending link
device of UE is higher in cost, so most UE has only one uplink
sending link, but has more (usually two) downlink receiving links.
On such a basis, a downlink channel matrix of the UE corresponds to
2.times.N.sub.T (N.sub.T represents a number of downlink antennae)
channels, while the Node B may only obtain 1.times.N.sub.T channels
through the uplink SRS, that is, the uplink and downlink channels
only have the partial channel reciprocity. At this moment, the UE
may support downlink double-stream transmission. However, under the
limit of the partial channel reciprocity, the Node B cannot obtain
all channel information, and thus may perform downlink
single-stream transmission only. Therefore, system resources are
not fully utilized, and system performance is reduced.
[0079] Based on the above problems and technical thoughts, besides
that "a Node B configures a first CSI-RS and ports configured to
send the first CSI-RS, and sends the first CSI-RS to UE at the
configured ports, the first CSI-RS being configured for the UE to
perform downlink channel measurement and feed back the first
downlink channel information", technical contents involved in the
embodiments of the disclosure further include:
[0080] a: the first CSI-RS configured by the Node B for the UE is a
precoded CSI-RS;
[0081] b: a number of the ports configured by the Node B to send
the first CSI-RS is smaller than or equal to a number of receiving
antennae of the UE;
[0082] c: the number of the ports configured by the Node B to send
the first CSI-RS is two, and the two ports correspond to different
polarization directions of antennae of the Node B;
[0083] d: the first downlink channel information fed back by the UE
on the basis of the first CSI-RS includes a CQI and/or a PMI;
[0084] e: the Node B configures a second CSI-RS and ports
configured to send the second CSI-RS, and the UE feeds back a
channel RI on the basis of the second CSI-RS;
[0085] f: the second CSI-RS configured by the Node B for the UE is
an un-precoded CSI-RS;
[0086] g: the Node B sends the second CSI-RS on part of occupied
antennae; and
[0087] h: the number of the ports configured by the Node B to send
the first CSI-RS is smaller than or equal to a number of the ports
configured to send the second CSI-RS.
[0088] It is important to note that any one of the technical
contents may be an independent technical content, and may also be
combined.
[0089] The embodiments of the disclosure will be further described
below in detail in combination with the drawings of the
specification.
[0090] FIG. 1 is a flowchart of a channel information feedback
method according to some embodiments of the disclosure. The method
includes the following steps.
[0091] In S101, a Node B configures a first CSI-RS and ports
configured to send the first CSI-RS.
[0092] In S102, the Node B sends the first CSI-RS to UE at the
configured ports, the first CSI-RS being configured for the UE to
perform downlink channel measurement and feed back first downlink
channel information.
[0093] Optionally, the first CSI-RS is a precoded CSI-RS
(corresponding to the technical content "a").
[0094] In a specific implementation, for the problem that a
transmission mode corresponding to a CQI is mismatched with a
transmission mode practically adopted by the Node B for downlink
data transmission, the Node B may pre-code a CSI-RS by adopting a
precoding matrix adopted for downlink data transmission, and at
this moment, because a precoding matrix corresponding to the CSI-RS
is the same as the precoding matrix adopted for downlink data
transmission, the CQI fed back by the UE is matched with an MCS
adopted for downlink data transmission.
[0095] In S102, the first downlink channel information is
configured for the Node B to determine coding information used when
downlink data is sent to the UE. Optionally, the first downlink
channel information includes a CQI and/or a PMI (corresponding to
the technical content "d").
[0096] Specifically, if the first CSI-RS is a CSI-RS of two ports,
the first downlink channel information includes the CQI and the
PMI; and if the first CSI-RS is a CSI-RS of a single port, the
first downlink channel information includes the CQI.
[0097] Wherein, when the number of the ports configured to send the
first CSI-RS is two, the two ports correspond to different
polarization directions of antennae of the Node B (corresponding to
the technical content "c").
[0098] In a specific implementation, the UE may measure downlink
channel information on the basis of the precoded CSI-RS and feed
back the CQI. For the condition that only single-stream
transmission is required, a single-stream precoding matrix required
for sending the CSI-RS may be obtained on the basis of channel
reciprocity, wherein, for the condition of complete channel
reciprocity, the single-stream precoding matrix may be obtained by
channel eigenvalue decomposition, and for the condition of partial
channel reciprocity, the single-stream precoding matrix may be
obtained by simple channel conjugate transposition without obvious
performance reduction. For the condition that double-stream
transmission is required, all information of a double-stream
precoding matrix required for sending the CSI-RS cannot be directly
obtained on the basis of the partial channel reciprocity (part of
information may be obtained). A process of configuring the first
CSI-RS on the basis of the channel reciprocity is as follows: the
Node B determines uplink channel information according to an uplink
SRS sent by the UE; second downlink channel information is
estimated on the basis of the determined uplink channel
information, and precoding matrix information (which is the
single-stream precoding matrix in case of single-stream
transmission, and is part of information of the double-stream
precoding matrix (such as V mentioned below) in case of
double-stream transmission) used when downlink data is sent to the
UE is determined on the basis of the estimated second downlink
channel information; and the first CSI-RS is configured on the
basis of the determined precoding matrix information.
[0099] A dual-polarized antenna is a main antenna type of the Node
B, and a larger number of antennae may be carried on a limited
antenna surface. One of characteristics of the dual-polarized
antenna is that a channel correlation between two polarization
directions is very low, and the channels may usually be represented
as [V1, a V2] (corresponding to channels of a receiving antenna),
wherein V1 and V2 represent information of the two polarization
directions respectively, and .alpha. represents a phase difference
between the two polarization directions and is a complex constant
of which a modulus is 1. Under a normal condition, the two
polarization directions are similar, that is, V1=V2, and at this
moment, channels of a single receiving antenna may be represented
as [V, .alpha. V]. Here, V corresponds to a physical direction, and
V of different receiving antennae is almost constant when a
communication distance is much longer than an interval between the
receiving antennae. The phase difference is formed by combining
multiple paths, and a tiny positional change may cause a different
phase difference. Therefore, different receiving antennae usually
have the same V but mutually independent phase differences. For
example, channels of different receiving antennae are [V, .alpha.
V; V, .beta. V].
[0100] Based on the above characteristic of the dual-polarized
antenna, for double-stream transmission, a probability of using a
dual-polarized antenna is greatly higher than a probability of
using a single-polarized antenna, wherein a precoding matrix of a
first stream is usually [V, .theta. V], a precoding matrix of a
second stream is [V, -.theta. V], and here, V may be determined
practically on the basis of the uplink SRS. Therefore, for
determining a downlink data precoding matrix, it is practically
only necessary to obtain a phase difference .theta. (corresponding
to the PMI) between the two polarization directions. Here, .theta.
is the phase difference in the precoding matrix, and cannot be
obtained through the channel reciprocity.
[0101] For obtaining .theta., the two-port CSI-RS corresponding to
the two polarization directions may be downlink precoded and sent
to the UE in the embodiment of the disclosure. The precoding matrix
of the two-port CSI-RS is V, and here, V may be determined on the
basis of partial channel reciprocity. When receiving the two-port
CSI-RS, the UE performs downlink channel measurement on the basis
of the two-port CSI-RS, and feeds back the phase difference .theta.
of the precoding matrix and the CQI to the Node B on the basis of a
measurement result. The Node B may determine the precoding matrix
and MCS used for downlink data transmission by virtue of the phase
difference .theta. and the CQI, as shown in FIG. 2.
[0102] In a specific implementation, when the two-port CSI-RS is
precoded, the same precoding matrix may be used, and different
precoding matrixes may also be used. Specifically, the Node B may
determine a precoding matrix corresponding to the CSI-RS of each
port according to a channel reciprocity result. The method may also
be applied to an FDD system, besides a TDD system, and at this
moment, the precoding matrix corresponding to the CSI-RS may be
determined on the basis of long-term channel reciprocity.
[0103] Optionally, the number of the ports configured to send the
first CSI-RS is smaller than or equal to the number of receiving
antennae of the UE (corresponding to the technical content
"b").
[0104] In the embodiment of the disclosure, in order to achieve a
purpose of reducing reference signal overhead, the number of the
antenna ports configured for the first CSI-RS is smaller than or
equal to the number of the receiving antennae of the UE.
[0105] Optionally, the operation that the Node B configures the
first CSI-RS in S101 includes that:
[0106] when the UE is required to perform single-stream
transmission, the Node B configures a first CSI-RS of a single
port; and
[0107] when the UE is required to perform double-stream
transmission, the Node B configures a first CSI-RS of two ports,
the two ports corresponding to different polarization directions of
the antennae of the Node B.
[0108] In a specific implementation process, when the UE is only
required to perform single-stream transmission, for reducing the
overhead, the Node B is only required to send the CSI-RS of the
single port (simultaneously corresponding to the two polarization
directions). When the UE is required to perform double-stream
transmission, the Node B may configure the CSI-RS of the two ports,
the two ports corresponding to different polarization directions of
the antennae of the Node B. On such a basis, the Node B may
determine whether the UE is required to perform single-stream
transmission or double-stream transmission at first.
[0109] Optionally, before the operation that the Node B configures
the first CSI-RS and the ports configured to send the first CSI-RS,
the method further includes that:
[0110] the Node B configures a second CSI-RS and ports configured
to send the second CSI-RS; and
[0111] the Node B sends the second CSI-RS to the UE at the ports
configured to send the second CSI-RS, the second CSI-RS being
configured for the UE to feed back a channel RI (corresponding to
the technical content "e").
[0112] Optionally, the second CSI-RS is a un-precoded CSI-RS
(corresponding to the technical content "f").
[0113] In the embodiment of the disclosure, the Node B may send an
un-precoded CSI-RS, and the UE performs channel measurement on the
basis of the un-precoded CSI-RS, and feeds back a corresponding
channel RI to notify a number of streams downlink-transmitted by
the Node B, that is, the Node B may determine whether the UE is
required to perform single-stream transmission or double-stream
transmission on the basis of the RI fed back by the UE. Since an RI
may change slowly, an RI sending period of the Node B may be
longer, which may reduce CSI-RS overhead. Here, the CSI-RS which is
configured to feed back the RI and un-precoded is called as an
RI-RS, and the CSI-RS configured to feed back the phase difference
(corresponding to the PMI) is called as a short-term CSI-RS (with a
shorter sending period). FIG. 3 is a schematic diagram of sending
an RI-RS and a short-term CSI-RS.
[0114] Optionally, the operation that the Node B sends the second
CSI-RS to the UE includes that:
[0115] the Node B sends the second CSI-RS to the UE on part of
occupied antennae (corresponding to the technical content "g").
[0116] In a specific implementation process, for further reducing
the reference signal overhead, the second CSI-RS may not be
required to correspond to all antennae, but may correspond to a few
antennae which are at longer distances (longer than a preset
distance) or have different polarization directions. As shown in
FIG. 4, a 64-antenna system may feed back an RI by using a CSI-RS
of only four ports, the four ports are at longer distances, and the
port 1 and the port 2 correspond to a polarization direction
different from the port 3 and the port 4.
[0117] Optionally, the number of the ports configured to send the
first CSI-RS is smaller than or equal to a number of the ports
configured to send the second CSI-RS (corresponding to the
technical content "h").
[0118] Optionally, the operation that the Node B configures the
first CSI-RS includes that:
[0119] the Node B configures the second CSI-RS and the ports
configured to send the second CSI-RS;
[0120] the Node B sends the second CSI-RS to the UE at the ports
configured to send the second CSI-RS to enable the UE to feed back
third downlink channel information;
[0121] the Node B determines precoding matrix information used when
downlink data is sent to the UE on the basis of the third downlink
channel information fed back by the UE; and
[0122] the Node B configures the first CSI-RS on the basis of the
determined precoding matrix information.
[0123] In a specific implementation process, in the FDD system, if
the long-term channel reciprocity is not used, the second CSI-RS
(or called as an RI-RS and a long-term CSI-RS) may be configured to
feed back long-term channel information (such as the abovementioned
V), and the Node B may pre-code a short-term CSI-RS (the first
CSI-RS) by using the long-term channel information. Under such a
condition, it is only necessary to perform codebook design for the
long-term CSI-RS without a need to perform codebook design for the
short-term CSI-RS. Compared with the condition that long-term and
short-term CSI-RSs are not distinguished, the CSI-RS overhead may
be greatly reduced.
[0124] Based on the same inventive concept, the embodiments of the
disclosure provide a channel information feedback method for a UE
side corresponding to the channel information feedback method for a
Node B side, and parts, repeated with the contents introduced for
the Node B side, about specific implementation will not be
elaborated.
[0125] FIG. 5 is a flowchart of a channel information feedback
method according to some other embodiments of the disclosure. The
method includes the following steps.
[0126] In S501, UE receives a first CSI-RS sent by a Node B.
[0127] In S502, the UE performs downlink channel measurement to
determine first downlink channel information on the basis of the
first CSI-RS.
[0128] In S503, the UE feeds back the first downlink channel
information to the Node B.
[0129] Optionally, the first CSI-RS is a precoded CSI-RS.
[0130] Optionally, the first downlink channel information includes
a CQI and/or a PMI.
[0131] Optionally, if the first CSI-RS is a CSI-RS of two ports,
the first downlink channel information includes the CQI and the
PMI; and
[0132] if the first CSI-RS is a CSI-RS of a single port, the first
downlink channel information includes the CQI.
[0133] Optionally, before the operation that the UE receives the
first CSI-RS sent by the Node B, the method further includes
that:
[0134] the UE receives a second CSI-RS sent by the Node B; and
[0135] the UE performs downlink channel measurement on the basis of
the second CSI-RS, and feeds back a channel RI on the basis of a
channel measurement result.
[0136] Optionally, before the operation that the UE receives the
first CSI-RS sent by the Node B, the method further includes
that:
[0137] the UE receives the second CSI-RS sent by the Node B;
and
[0138] the UE performs downlink channel measurement on the basis of
the second CSI-RS, and feeds back third downlink channel
information, the third downlink channel information being
configured for the Node B to determine precoding matrix information
for configuring the first CSI-RS.
[0139] Optionally, the second CSI-RS is a precoded CSI-RS.
[0140] Specific implementations will be described below from the
aspect of interaction between a Node B and UE.
[0141] FIG. 6 is a flowchart of a channel information feedback
method according to some other embodiments of the disclosure. The
method includes the following steps.
[0142] In S601, the Node B configures an un-precoded CSI-RS and
ports configured to send the un-precoded CSI-RS, and sends the
un-precoded CSI-RS to the UE at the ports configured to send the
un-precoded CSI-RS.
[0143] Here, the Node B may send the un-precoded CSI-RS to the UE
only on part of occupied antennae, that is, the ports for sending
the un-precoded CSI-RS are part of ports in all antenna ports of
the Node B.
[0144] In S602, the UE receives the un-precoded CSI-RS from the
Node B, performs downlink channel measurement on the basis of the
un-precoded CSI-RS, and feeds back a channel RI indicating
single-stream transmission or double-stream transmission on the
basis of a channel measurement result.
[0145] In S603, the Node B determines whether the UE is required to
perform single-stream transmission or double-stream transmission on
the basis of the RI fed back by the UE, enters S604 if
single-stream transmission is required, otherwise enters S606.
[0146] In S604, the Node B configures a precoded CSI-RS of a single
port and the single port configured to send the precoded CSI-RS,
and sends the precoded CSI-RS to the UE at the configured single
port.
[0147] In S605, the UE feeds back a CQI to the Node B on the basis
of the received precoded CSI-RS of the single port.
[0148] In S606, the Node B configures a precoded CSI-RS of two
ports and the two ports configured to send the precoded CSI-RS, the
two ports corresponding to different polarization directions of
antennae of the Node B, and sends the precoded CSI-RS to the UE at
the configured two ports.
[0149] Here, a number of ports configured to send the precoded
CSI-RS is smaller than or equal to a number of receiving antennae
of the UE. The number of the ports configured to send the precoded
CSI-RS is smaller than or equal to a number of ports configured to
send the un-precoded CSI-RS.
[0150] In S607, the UE feeds back the CQI and a PMI to the Node B
on the basis of the received precoded CSI-RS of the two ports.
[0151] Based on the same inventive concept, the embodiments of the
disclosure further provide a channel information feedback device
corresponding to the channel information feedback method. A
principle for shoving problems of the device is similar to the
channel information feedback method of the embodiments of the
disclosure, and implementation of the device may thus refer to
implementation of the method, and repeated parts will not be
elaborated.
[0152] FIG. 7 is a structure diagram of a channel information
feedback device according to some other embodiments of the
disclosure. The device includes:
[0153] a configuration module 71, configured to configure a first
CSI-RS and ports configured to send the first CSI-RS; and
[0154] a sending module 72, configured to send the first CSI-RS to
UE at the configured ports, the first CSI-RS being configured for
the UE to perform downlink channel measurement and feed back first
downlink channel information.
[0155] Optionally, the first CSI-RS is a precoded CSI-RS.
[0156] Optionally, a number of the ports configured to send the
first CSI-RS is smaller than or equal to a number of receiving
antennae of the UE.
[0157] Optionally, the number of the ports configured to send the
first CSI-RS is two, and the two ports correspond to different
polarization directions of antennae of a Node B.
[0158] Optionally, the first downlink channel information includes
a CQI and/or a PMI.
[0159] Optionally, if the first CSI-RS is a CSI-RS of two ports,
the first downlink channel information includes the CQI and the
PMI; and
[0160] if the first CSI-RS is a CSI-RS of a single port, the first
downlink channel information includes the CQI.
[0161] Optionally, the configuration module 71 is specifically
configured to:
[0162] when the UE is required to perform single-stream
transmission, configure a first CSI-RS of a single port; and
[0163] when the UE is required to perform double-stream
transmission, configure a first CSI-RS of two ports, the two ports
corresponding to different polarization directions of the antennae
of the Node B.
[0164] Optionally, the configuration module 71 is further
configured to: before configuring the first CSI-RS and the ports
configured to send the first CSI-RS, configure a second CSI-RS and
ports configured to send the second CSI-RS; and
[0165] the sending module is further configured to: send the second
CSI-RS to the UE at the ports configured by the configuration
module to send the second CSI-RS, the second CSI-RS being
configured for the UE to feed back a channel RI.
[0166] Optionally, the second CSI-RS is an un-precoded CSI-RS.
[0167] Optionally, the sending module 72 is specifically configured
to:
[0168] send, by the Node B, the second CSI-RS to the UE on part of
occupied antennae.
[0169] Optionally, the number of the ports configured to send the
first CSI-RS is smaller than or equal to a number of the ports
configured to send the second CSI-RS.
[0170] Optionally, the configuration module 71 is specifically
configured to:
[0171] determine uplink channel information according to an uplink
SRS sent by the UE;
[0172] estimate second downlink channel information on the basis of
the determined uplink channel information, and determine precoding
matrix information when downlink data is sent to the UE on the
basis of the estimated second downlink channel information; and
[0173] configure the first CSI-RS on the basis of the determined
precoding matrix information.
[0174] Optionally, the configuration module 71 is specifically
configured to:
[0175] configure the second CSI-RS and the ports configured to send
the second CSI-RS;
[0176] send the second CSI-RS to the UE at the ports configured to
send the second CSI-RS to enable the UE to feed back third downlink
channel information;
[0177] determine the precoding matrix information when the downlink
data is sent to the UE on the basis of the third downlink channel
information fed back by the UE; and
[0178] configure the first CSI-RS on the basis of the determined
precoding matrix information.
[0179] FIG. 8 is a structure diagram of a channel information
feedback device according to some other embodiments of the
disclosure. The device includes:
[0180] a receiving module 81, configured to receive a first CSI-RS
sent by a Node B;
[0181] a determination module 82, configured to perform downlink
channel measurement to determine first downlink channel information
on the basis of the first CSI-RS; and
[0182] a sending module 83, configured to feed back the first
downlink channel information to the Node B.
[0183] Optionally, the first CSI-RS is a precoded CSI-RS.
[0184] Optionally, the first downlink channel information includes
a CQI and/or a PMI.
[0185] Optionally, if the first CSI-RS is a CSI-RS of two ports,
the first downlink channel information includes the CQI and the
PMI; and
[0186] if the first CSI-RS is a CSI-RS of a single port, the first
downlink channel information includes the CQI.
[0187] Optionally, the receiving module 81 is further configured
to: before receiving the first CSI-RS sent by the Node B, receive a
second CSI-RS sent by the Node B; and
[0188] the sending module 83 is further configured to: perform
downlink channel measurement on the basis of the second CSI-RS, and
feed back a channel RI on the basis of a channel measurement
result.
[0189] Optionally, the receiving module 81 is further configured
to: before receiving the first CSI-RS sent by the Node B, receive
the second CSI-RS sent by the Node B; and
[0190] the sending module 83 is further configured to: perform
downlink channel measurement on the basis of the second CSI-RS, and
feed back third downlink channel information, the third downlink
channel information being configured for the Node B to determine
precoding matrix information for configuring the first CSI-RS.
[0191] Optionally, the second CSI-RS is an un-precoded CSI-RS.
[0192] Those skilled in the art should know that the embodiment of
the disclosure may be provided as a method, a system or a computer
program product. Therefore, the disclosure may adopt a form of pure
hardware embodiment, pure software embodiment and combined software
and hardware embodiment. Moreover, the disclosure may adopt a form
of computer program product implemented on one or more
computer-available storage media (including, but not limited to, a
disk memory, a Compact Disc Read-Only Memory (CD-ROM) and an
optical memory) including computer-available program codes.
[0193] The disclosure is described with reference to flowcharts
and/or block diagrams of the method, device (system) and computer
program product according to the embodiment of the disclosure. It
should be understood that each flow and/or block in the flowcharts
and/or the block diagrams and combinations of the flows and/or
blocks in the flowcharts and/or the block diagrams may be
implemented by computer program instructions. These computer
program instructions may be provided for a universal computer, a
dedicated computer, an embedded processor or a processor of other
programmable data processing equipment to generate a machine, so
that a device for realizing a function specified in one flow or
more flows in the flowcharts and/or one block or more blocks in the
block diagrams is generated by the instructions executed through
the computer or the processor of the other programmable data
processing equipment.
[0194] These computer program instructions may also be stored in a
computer-readable memory capable of guiding the computer or the
other programmable data processing equipment to work in a specific
manner, so that a product including an instruction device may be
generated by the instructions stored in the computer-readable
memory, the instruction device realizing the function specified in
one flow or many flows in the flowcharts and/or one block or many
blocks in the block diagrams.
[0195] These computer program instructions may further be loaded
onto the computer or the other programmable data processing
equipment, so that a series of operating steps are executed on the
computer or the other programmable data processing equipment to
generate processing implemented by the computer, and steps for
realizing the function specified in one flow or many flows in the
flowcharts and/or one block or many blocks in the block diagrams
are provided by the instructions executed on the computer or the
other programmable data processing equipment.
[0196] Although the optional embodiments of the disclosure have
been described, those skilled in the art may make additional
variations and modifications to these embodiments once learning
about the basic creative concept. Therefore, the appended claims
are intended to be interpreted to include preferred embodiments and
all variations and modifications falling within the scope of the
disclosure.
[0197] Obviously, those skilled in the art may make various
modifications and transformations to the disclosure without
departing from the spirit and scope of the disclosure. Therefore,
if these modifications and transformations of the disclosure fall
within the scope of the claims of the disclosure and an equivalent
technology thereof, the disclosure is also intended to include
these modifications and transformations.
* * * * *